I play MW3 a lot with my nephews, and they say that Black Ops is better. Haven't heard anything about BF3 though.
I can say that I get really frustrated with my inability to see other players in MW3. All I ever see is bullets flying and my sorry arse falling to the ground. On top of this, I think the most kills I've ever gotten in Deathmatch is 4, but then again I have a life and play it every once in a while.